1. Field of Invention
This invention relates to combustion devices, and more particularly to a pellet fuel feed mechanism, and even more particularly to a vibratory feed mechanism for moving pelletized fuel from a fuel reservoir to a fire pot in a combustion device for generating heat.
2. Background and Description of Prior Art
For centuries wood has been burned in pits, fireplaces, stoves, and barbeques to provide heat. Over time, the methods and apparatus in which wood was burned to provide heat improved. For instance, pits led to hearths. Hearths led to stoves. Stoves led to furnaces and registers. Many of these improvements followed or resulted from advances in science, advancements in manufacturing, and also the availability of resources.
Similar to changes and advancements in the apparatus used to generate heat, advancements also followed for fuels used with those apparatus' for generating heat with the goal of providing more heart per unit of fuel, lower cost, easier storage, reduced risk of undesirable fires and reduced waste products such as smoke, ash, and soot.
Various of these advancements led to the development of pellet fuel stoves and pelletized fuel. One of the many reasons pellet fuel stoves have become popular is because pelletized fuel can be manufactured from products that would otherwise be waste products, such as sawdust, wood bark, rice hulls, walnut shells and the like. As such, pelletized fuel has remained relatively inexpensive as compared to wood, oil, coal or natural gas. Further pelletized fuel is easy to store and does not readily burn without forced air and therefore presents a reduced fire risk.
Unfortunately, known pellet fuel combustion devices, including but not limited to pellet fuel stoves and pellet fuel barbeques suffer from a universal problem that is inherent in known pellet fuel feed mechanisms by which the pelletized fuel is moved from a fuel reservoir, to a fire pot where the fuel is combusted to generate heat.
In known pellet fuel combustion devices, a rotating feed auger is used to move the pelletized fuel from the fuel reservoir to a drop chute where the pelletized fuel moves under the force of gravity, downwardly to the fire pot where combustion takes place. The feed auger is commonly powered by an electric motor and a reduction gear assembly that rotates the auger responsive to a signal received from a control panel and a thermocouple. The feed auger is commonly carried within an auger tube having a first end portion and second end portion. The fuel reservoir communicates with the first end portion of the auger tube so that the pelletized fuel is deposited into the auger tube at the first end portion and rotation of the auger moves the pelletized fuel from the first end portion to the second end portion that communicates with the drop tube. For safety reasons, the second end portion of the drop tube is vertically and horizontally spaced apart from the fire pot to prevent a “burn back” where pellet fuel within the auger tube might catch fire and “burn back” to the fuel reservoir.
Over the periods of use, the feed auger will start and stop many thousands of times responsive to receiving a signal from the control board and the thermocouple to move additional fuel pellets from the fuel reservoir to the drop tube to feed the fire pot to maintain a desired level of heat. The starting and stopping of the auger motor, the reduction gear assembly and the auger causes wear to the various mechanical components and frequently leads to the mechanical parts being noisy. Further, because the fuel pellets have “rough” surfaces that enhance the tendency to “catch” fire, the fuel pellets also have the tendency to “wear on” and “abrade” the surfaces of the auger tube and the auger, which after periods of use may cause “gaps” and “spaces” between edge portions of the auger and the auger tube where fuel pellets may become “caught” and “trapped” causing binding such that the auger may not spin freely within the auger tube. Such binding exacerbates the wear on the auger, the auger tube, the reduction gears and the auger motor.
It is well known in the pellet stove industry that the primary cause of breakdown and dysfunction of pellet fuel combustion devices is malfunction and wearing out of the auger, the auger motor and the auger reduction gear assembly which may collectively be referred to as the “feed mechanism.” Further, one of the primary complaints of pellet fuel combustion devices is the noise generated by the starting and stopping of the feed mechanism.
Because pellet fuel combustion devices require regular periodic feeding of fuel pellets to operate, when the auger, the auger motor, or the reduction gear assembly malfunction, the pellet fuel combustion device is inoperable, will not generate heat, which may in some instances, lead to significant damage to the user's premises, such as frozen pipes, and the like.
What is needed is a feed mechanism for pellet fuel combustion devices that does not suffer from the same drawbacks as auger feed mechanisms. What is needed is a pellet fuel feed mechanism that eliminates the mechanical interconnection of an auger motor, a reduction gear assembly and an auger that rotates axially within an auger tube. Elimination of the mechanical interconnection of these various components significantly reduces the likelihood of failure, the amount of wear-and-tear subjected upon the components, and also eliminates the noise generated by the mechanically interconnected moving parts.
My vibratory feed mechanism for pellet fuel combustion devices overcomes various of the aforementioned drawbacks by providing a spring supported feed plate that is vibrated by an electric motor carrying an offset counterweight. The spinning of the counterweight by the vibration motor causes the feed plate to vibrate which responsively causes fuel pellets to move along an upper surface of the feed plate from a fuel reservoir to a metering channel and a drop tube for conveyance of the fuel pellets to a fire pot. The spring mounting of the feed plate dampens noise and eliminates transfer of the vibration to the stove. The absence of an auger, an auger motor and a reduction gear assembly reduces wear and tear, reduces maintenance and reduces noise.
My vibratory feed mechanism will operate with various forms of pelletized fuel including, but not limited to, fuel pellets formed of wood, wood products, wood by-products, corn, rice hulls, walnut hulls, nut shells and biomass. All of these named fuel types, and others not named, are available, or are contemplated as being available, in pelletized form.
Some or all of the drawbacks and problems explained above, and other drawbacks and problems, may be helped or solved by my invention shown and described herein. My invention may also be used to address other problems not set out herein or which become apparent at a later time. The future may also bring to light unknown benefits which may, in the future, be appreciated from the novel invention shown and described herein.
My invention does not reside in any one of the identified features individually, but rather in the synergistic combination of all of its structures, which give rise to the functions necessarily flowing therefrom as hereinafter specified and claimed.